“How Wolves Change Rivers” Video is a Myth

Not too long ago, well-known British filmmaker George Monbiot turned a new film loose on the masses entitled “How Wolves Change Rivers.” It made big waves among the anti-hunting crowd.

The film’s main purpose was to introduce a “brand new” concept to the public called the “Trophic Cascade.” I’m not going to spend much time explaining the Trophic Cascade theory, largely because it’s not new. Aldo Leopold showed us in “A Sand County Almanac,” published nearly 70 years ago, that the natural world is connected in ways we know, and in ways we don’t yet know. What happens to the bottom of the chain affects the top, and vice-versa.

If you live in a social media vacuum you might not be familiar with how nature works, but those of us who spend time in the field understand it well. We can see through the hype used by animal rights and environmental extremists to skew story lines. It’s a recurring tactic used to tilt the scales toward their goal, which in this case is to ban all predator hunting. It’s fair to point out obvious manipulations of information to people who might otherwise miss it.

Now, back to the movie …

If you haven’t watched the video, the footage is beautiful and brief: 4 minutes and 33 seconds, the perfect length for short attention spans and malleable minds. I’ll only briefly mention its glaring errors, like the use of stock imagery from other parts of the world to illustrate the Yellowstone ecosystem. (That’s a European Badger, not American Badger at the 2:43 mark.) You also could comment on Monbiot’s incessant use of the word “deer” when he really means “elk,” but that can be forgiven since Brits call their version of wapiti “red deer” and sometimes refer to our moose as elk. That’s cultural, and excusable.

Instead, I’ll focus on the film’s most egregious and deliberate tricks. First up: the use of site-specific locations inside Yellowstone National Park, which are rarely used by elk, to illustrate the argument that wolves prevent herbivores from denuding river corridors, thus allowing riparian habitat to regenerate. You cannot use footage from other rivers—some not even in Yellowstone—to show how the Lamar River has recovered “because of wolves.”

That Trophic Cascade effect was an attractive potential outcome to some people early in the wolf-reintroduction process. In those days, park scientists had high hopes for the famous Lamar Valley and the return of the aspens, cottonwoods and willows along the river. When wolves were reintroduced into the valley in 1995, there were tens of thousands of elk, bison and deer in the park. Those large herbivores were, of course, nonstop eating machines. If they could reach it, they ate it.

With the wolf comeback, herds scattered and spread out the vegetative consumption, but it didn’t last. The large plant-eaters learned to cope with the new predator, and today if you travel to the valley you will see it’s much the same as it was pre-wolf: small pockets of trees growing along the river and not much young growth.

“Exclosure fences” throughout Yellowstone, designed to keep the plant eaters out, demonstrate what could and would grow if not for the thousands of ungulates eating the young trees and shrubs.

Too make the footage more dramatic, videographers resorted to deceit, and that’s the crux of the issue with Monbiot. He is a well-known investigative journalist in Great Britain, famous for pointing out falsehoods and errors, so it’s fair he should come under the same scrutiny.

Monbiot’s film shows some scenes of intact riparian habitat inside the park, but the footage is not from the Lamar Valley. It is from the rugged Grand Canyon of the Yellowstone, where it’s difficult for any herbivores to thrive. The river corridor there is ecologically intact not because of wolves. It survives because the geography leaves little space for elk. It’s all about terrain. Other footage, like the bull moose in the lush cottonwoods at the 1:55 mark, isn’t even from inside Yellowstone.

Monbiot pretends he’s showing the results of wolves coming back to Lamar, but he’s not. The idea that wolves have altered the landscape in a physical way, as the film suggests, is hype. Fortunately, unlike Monbiot, actual scientists are focused on the truth and are calling out the film on its factual errors.

Studies by Tom Hobbs, Kristin Marshall and David Cooper of Colorado State University's Natural Resource Ecology Laboratory show that while wolves have certainly had an impact on the ecology of Yellowstone, the real key to the rivers there isn’t wolves. In a recent AccuWeather story debunking the video, Hobbs says, "It's a lovely story, and I would love this to be true, but it isn't. [The video] is demonstratively [sic] false."

Utah State University ecologist Dan McNulty, who worked in Yellowstone with the wolf project for years, agreed. "It's a really romantic story. It's a story about a world that doesn't really exist."

Instead, current research shows beavers are far more important to Yellowstone’s rivers than wolves since beavers actually do “change rivers.” But beavers need streamside vegetation to survive, and streamside vegetation needs the beavers to create the habitat. And those streamside plants, especially willows, never have a chance to grow with Yellowstone’s ungulate population continually pruning them down to the roots. It’s a vicious circle unlikely to be resolved anytime soon—with or without wolves.

In fact, since wolves also eat beavers, perhaps they are negatively affecting rivers. A 2015 Minnesota study concluded that at certain times of year, beavers form as much as 34 percent of the wolves’ diet. Wolves, like most predators, are opportunists. That’s why they are successful.

In addition to beavers, or rather their absence, Hobbs also suggests that changes in precipitation, stream flow, floodplains and water tables are also major contributing factors in the state of the vegetation.

Media manipulation and films like “How Wolves Change Rivers” are nothing new, but delving deeper into the producer’s intent raises serious questions. Monbiot and Company knew their information was not current or accurate. The real story—the story that wolves are not “ecosystem engineers” as Monbiot calls them—didn’t fit their narrative, so they ignored it. That is intolerable from a journalistic standpoint. And remember: Monbiot is an award-winning journalist.

What is ultimately required is a scientific, not sensational approach to determining just what wolves can and cannot do for the environment. As Princeton Biologist Andy Dobson stated in a 2014 paper:

“… we need many more ecosystem-level studies of how species interactions between predators, parasites, and prey change the patterns of spatial heterogeneity in vegetation that ultimately drive levels of biodiversity at higher trophic levels… This is an exercise that requires a new generation of… multitrophic models and many more debates such as the current one about the role of wolves in Yellowstone.”

In simpler terms, we don’t know what we don’t know. Further investigation is needed and it’s far too early to make claims like “wolves change rivers.”

So what? I mean, how many people will really care about a 4-minute film made by a Brit known for stirring up controversy? Let’s explain it this way. To date 39 million people have watched the video on YouTube. Thousands more have seen his TED talk on the subject. Most of them are young and will never see a wolf, an elk or even a river in Yellowstone, but they believe what the video tells them. And every time the subject of predator management comes up on social media, the usual suspects trot out this little film.